Cu-ion-actuated three-terminal neuromorphic synaptic devices based on binary metal-oxide electrolyte and channel

An analogous change in lateral channel current from source to drain in three-terminal synaptic devices actuated by mobile ions vertically provided from a gate can enhance neuromorphic computing performances. We demonstrate a gradually tuned channel current in a fully complementary metal-oxide-semiconductor compatible HfOx/WOx stack with Cu ions. By examining each layer in the three-terminal device, such as the channel, electrolyte, and mobile ion supplier, we identify which device structure can modulate the channel current effectively using mobile ions. Our findings reveal that the gate-tunable channel current response can be solely achieved when the Cu ions are not locally formed but migrate throughout the HfOx electrolyte. The linear dependence of the analog current operation on the channel width further proves the area-switching mechanism. The importance of ion movement can be indirectly verified from the uncontrollable channel currents using either Ag ions with faster mobility than Cu ions or a local path is created because of the thinned HfOx electrolyte.